I have a coleman on the roof of rv but want to replace it with a dometic. How should it be done?
I will assume that you are aware of the fact that both upper ( unit on roof ) and lower control unit ( inside at ceiling ) will need to be replaced. That obviously adds to cost, instead of just replacing upper unit with same as what's there. Be sure to shut power off at breaker panel to start with. There is only 4 bolts, usually 1/4" with either 3/8" or 7/16" head, That holds the upper to lower. Once you remove them, and any extra screws that may go into ceiling from lower unit, the 2 pieces are separate. Disconnect any wiring ( mark wires if thermostatically operated) from lower unit, and if it's not ducted in the ceiling there will be ducting attached from upper to lower unit usually with flanges that have screws in them. 3 Philips screws where it attaches at base of upper unit, and that should drop down. That should be it. Now just lift unit on roof up and off. May take a bit off effort as some stick pretty good. Be sure to watch if you have a rubber roof that the rubber isn't ripping. I have had some that the person who installed it used some sealant at gasket surface, and had to very carefully lift and pry it apart, but as I said, if you find same, watch rubber for ripping. No need to apply anything to gasket if roof is clean, just set new one down over hole, even it up and draw down from inside with new ceiling assembly and bolts equally. Only compress gasket to approx 1/2 it's original thickness when tightening down, do not squish it.
SOURCE: Coleman Mach roof top ac
Under the drain pan on each side should be a small plastic drain plug they might be clogged up with debris.
SOURCE: roof gasket on rv a/c
Try not to compress gasket past 1/2 it's original thickness. Most of the factory ones have tabs that stick down, and supposedly when they touch the roof, it's far enough, which is about same as 1/2. I use my cordless with the torque setting on it, at about 2-3 until I see how far that draws down, then increase/decrease as needed from there.Once i feel it's 1/2 way, I torque all at same setting on drill to make sure all equal.
SOURCE: I''ve been working on this thing for three weeks
check the compressor winding resistance from common to start
start to run
run to common
the two lowest should equil the highest
also check shorted to ground
check the capacitors the go bad a lot
SOURCE: My Duo-therm Brisk-Air by Dometic rv ac wont cool.(The fan runs )
Usually just listening closely will give you a rough idea where to look for problem. When you have the fan on and switch to cool, (with temperature turned down low obviously) do you hear any type of "moaning" sounds from AC unit, or see lights in RV dim slightly indicating that compressor is trying to engage? Is the breaker tripping when compressor tries to engage? Do you hear a "click" from AC unit when switched to cool? If none of that happens, then I'd start thinking thermostat, or compressor relay. Normally if it's a faulty capacitor, the compressor will try to engage but will make a "moaning sound" and usually trip the breaker due to excess current draw. Someone experience in electrical should be able to test relays etc, but whoever does work on it, should be aware that those capacitors, as well as hydro in general are very dangerous to work with. The ("zap",- Shock) that you can experience from a capacitor or hydro, can be fatal.
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